I can really relate to that fear of being abandoned by a therapist. Any time I get the sense that there is a possibility my therapist will leave me I start to panic. It's an awful feeling and I've been there many times.
Lately what I have been thinking about working on is a cope ahead plan for what I would do if they left me. My theory is that if I have a plan for the worst case scenario and I can see myself getting through it, I can relax a little now. I'll have a plan so I won't need to constantly worry about it.
I feel for your shame too. It is such a toxic feeling that can make us feel like we're horrible human beings who need to be hidden. It's okay to experience shame but I hope you know there's nothing to be ashamed of. You are not bad or weird etc for looking up his partner. It's understandable that you'd do anything you could to learn of any hints that your therapist may leave because of your abandonment fears. I think any of us would do all we could to get ahead of something we fear so intensely so we aren't blindsided.
I hope you're able to have some compassion with yourself.